Hardware recommendations
 

I'm getting ready to replace my 4 year old Windows desktop and I'd like my next system to be optimized for serious factoring (140-150 digits). Anyone have specific hardware recommendations? I'm looking at the i7-990 CPU though I'm not clear if it's worth the extra cost over the i7-980. And I'm thinking 8gb of RAM but will 12gb be better? Does RAM speed have much impact? Any suggestions are welcome, thanks.

The first optimisation for serious factoring is to run 64-bit Linux; there's at least a factor two of performance from having access to the assembly optimisations in gnfs-lasieve4I14e. So you probably want to have one machine as your Windows desktop and another to do serious factoring.

And what you want from a factoring machine is lots of cheap cores; an i7-990 or i7-3830K is an awesome machine for doing linear algebra if someone else has done the sieving on a 180-digit number, but is not a good price-performance machine for doing sieving on.

I would get an AMD six-core Phenom with onboard graphics and 8G of memory; the board is about £65, the memory about £32, CPU is about £132 for a 3.2GHz six-core; with a small hard drive to store the relations and a case you're talking about £300.

I have roughly the system fivemack mentions; Lavalamp spelled out the parts in February or march or so of this year and I bought them. I've added a GTX440 GPU to it.

Do GPUs sieve yet? The only regret I had with that system is that I would have gotten a larger power supply to support a better GPU, such as the Nvidia GT560. Getting pin 997 on the CPU straightened out was a bit of a problem, and I have one chip that seems to run hot on the mobo, and I've been meaning to add a fan to run over that heatsink.

[QUOTE=fivemack;278726]The first optimisation for serious factoring is to run 64-bit Linux; there's at least a factor two of performance from having access to the assembly optimisations in gnfs-lasieve4I14e. So you probably want to have one machine as your Windows desktop and another to do serious factoring.

And what you want from a factoring machine is lots of cheap cores; an i7-990 or i7-3830K is an awesome machine for doing linear algebra if someone else has done the sieving on a 180-digit number, but is not a good price-performance machine for doing sieving on.

I would get an AMD six-core Phenom with onboard graphics and 8G of memory; the board is about £65, the memory about £32, CPU is about £132 for a 3.2GHz six-core; with a small hard drive to store the relations and a case you're talking about £300.[/QUOTE]I'd double the amount of memory and throw in a good CUDA-capable GPU such as the 560. Other than my GPU is a 460 (the 560 wasn't available when I bought my machine, Tom's system is a close match to mine. In particular, the unlocked AMD 1090 overclocks beautifully,

I also second the 64-bit Linux suggestion and would point out that if you really [b]need[/b] Windows and don't want to buy two systems, then VMware does a pretty good job,.

Paul

[QUOTE=xilman;278788]VMware does a pretty good job[/QUOTE]
Yuck! Long live VirtualBox from Sun (now Oracle)!
Seconding (or thirding?) everything else. A GPU (even a small one) worth all the money!

[QUOTE=LaurV;278844]Yuck! Long live VirtualBox from Sun (now Oracle)!
Seconding (or thirding?) everything else. A GPU (even a small one) worth all the money![/QUOTE]You are quite correct. In fact, I use VirtualBox myself. Both VB and VM do a pretty good job.

[QUOTE=Mr. Odd;278711]I'm getting ready to replace my 4 year old Windows desktop and I'd like my next system to be optimized for serious factoring (140-150 digits). Anyone have specific hardware recommendations? I'm looking at the i7-990 CPU though I'm not clear if it's worth the extra cost over the i7-980. And I'm thinking 8gb of RAM but will 12gb be better? Does RAM speed have much impact? Any suggestions are welcome, thanks.[/QUOTE]
If you can wait I strongly recommend buying an Intel Ivy Bridge processor (22nm shrink and new transistor technology) and a Nvidia Kepler generation GPU (28nm shrink) or ATI Southern Islands generation GPU (also 28nm) in late Q1/2012.

[QUOTE=fivemack;278726]The first optimisation for serious factoring is to run 64-bit Linux; there's at least a factor two of performance from having access to the assembly optimisations in gnfs-lasieve4I14e.

[/QUOTE]

Is that true for [FONT=monospace]gnfs-lasieve4I15e.exe[/FONT] and
[FONT=monospace]gnfs-lasieve4I16e.exe?[/FONT]

Yes; it's true for all the gnfs-lasieve4 tools, I just mentioned 14e because that's the one that you'll be using at 140-150 digits.

[QUOTE=LaurV;278844]Yuck! Long live VirtualBox from Sun (now Oracle)!
Seconding (or thirding?) everything else. A GPU (even a small one) worth all the money![/QUOTE]

A GPU is pretty much useless for GNFS factorisation - OK, it will speed up the polynomial selection a bit, but that's not the rate-determining step. And it does add quite perceptibly to the system's electricity usage even when not doing anything.

Ok, you've convinced me to go the Linux (Ubuntu)/VMWare route but I'm still planning on getting a NVidia 560XTi - I was under the impression that having a CUDA-enabled GPU definitely helped with YAFU and MSIEVE. Anyway, thanks for the input!